WO2004027492A1

WO2004027492A1 - Display unit and electronic apparatus equipped with display unit

Info

Publication number: WO2004027492A1
Application number: PCT/JP2003/012024
Authority: WO
Inventors: Tomohiro Sasagawa; Akimasa Yuuki; Naoto Sugawara
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 2002-09-19
Filing date: 2003-09-19
Publication date: 2004-04-01
Also published as: JPWO2004027492A1; CN1678943A; US20050276071A1; JP3930021B2; CN100376924C; US7210836B2

Abstract

A display unit comprising a light guide plate, light sources respectively disposed at two different light input end surfaces thereof, a double-sided prim sheet having a triangular prism row provided on a surface facing the light guide plate to extend in a direction parallel to the light input end surface of the light guide plate and a cylindrical lens row provided on a surface opposite to the above surface to extend in parallel to the triangular prism row, a transmission type display panel disposed on the output surface side of this double-sided prism sheet, and a synchronous drive means for displaying a parallax image on the transmission type display panel in synchronization with the light sources, wherein light rays from the light sources are respectively output from the transmission type display panel at angles corresponding to right and left parallaxes to enable a 3-D display.

Description

Display device and electronic device equipped with display device

The present invention relates to a display device, and more particularly to a display device used for a portable information terminal having a small display surface and capable of simultaneously displaying different screens with the same bright screen and the same bright screen. Fine

Background art

The stereoscopic display device generally presents an image having parallax from each viewpoint to the left and right eyes of the observer. Conventionally, there are two methods of presenting images having parallax to the left and right eyes of the observer, a method using special glasses and a method without glasses.

The method of using glasses is to switch the left and right parallax images that are displayed alternately in a time-division manner so that the glasses reach the left and right eyes of the observer through glasses.To present a stereoscopic display to the observer, the observer must Glasses must be worn, which is uncomfortable and annoying.

As a method not using glasses, a method using a lenticular lens or a paralux barrier is generally used. In this method, the display device displays left and right parallax images for each vertical pixel line, and the light emitted from each pixel line is guided to the left and right eyes of the observer. A lenticular lens and a parallax barrier are installed. Since it is necessary to display the left and right parallax images for each vertical pixel line of the display device, the image is divided into one line for the right and left for the number of pixels in the display device, resulting in an image with half the number of pixels . In the lenticular lens system, the lenticular Since it is difficult to switch the presence or absence of a single lens, it is necessary to display different pixel lines on the left and right eyes, as in a stereoscopic image, when displaying a planar image. Will drop. In the parallax barrier method, the parallax barrier itself is composed of a liquid crystal element, etc., so that the parallax barrier can be erased when displaying a flat image, so that the flat display is performed at the original resolution of the display panel. On the other hand, at the time of stereoscopic display, there is also a problem that the display becomes dark because a part of the light source light is blocked by a parallax barrier.

As a method of avoiding this problem, as in the case of using eyeglasses, the left and right parallax images are displayed in a time-division manner on a transmissive display panel, and the directivity of the light source that illuminates them is switched. There is a method to guide the parallax image to the left and right eyes respectively. For example, in the method proposed by the University of Kempty University shown in FIG. 22, a transmissive display panel 4, a collimating lens 6 provided on the rear surface, and further provided behind it, are sequentially provided. An array 7 of light sources that emit light is provided, and light emitted from the light source section 7a that emits light in the array of light sources is transmitted by a collimating lens 6 disposed in front of the light source section 7a. After passing through, it is converged with directivity. Therefore, the image on the transmissive display panel can be observed only in the direction in which it is converged. By switching between the light emitting part of the light source array and the parallax image displayed on the transmissive display panel in a synchronized manner, the left and right images can be viewed These parallax images are guided to the left and right eyes of the observer, respectively, enabling stereoscopic vision. This method of controlling the light emission position and using a lens with a collimating lens allows extremely accurate conversion of the position of the light emitting point on the light source into the angle of illumination light divided by the viewing position with the collimating lens. Good directionality of illumination light can be obtained, and high-quality stereoscopic vision can be achieved by good separation of left and right images.

As a method that can reduce the size of this method, for example, Japanese Patent Application Laid-Open Publication No. 63-106, Japanese Patent Application Laid-Open No. H10-161601 discloses a switchable stripe-shaped mask that switches light from a light source using a switchable element such as a liquid crystal element. A method has been proposed in which a lenticular sheet that divides a light source into a tris-like light source and acts as a collimating lens disposed after that is used to obtain the directivity of the light source. With this method, it is possible to display a stereoscopic image without reducing the resolution.However, since a part of the light source is shielded to create a striped light source, the light use efficiency is reduced and the display becomes darker. There is. Further, in addition to the display panel, an expensive liquid crystal shutter element or the like is required to produce a striped light source, so that there was a problem that it could not be constructed inexpensively. In addition, Japanese Patent Application Laid-Open No. 2001-66547 proposes a method shown in FIG. Rather than giving the directivity of the light source with a collimator lens, a prism sheet 8 is placed under the liquid crystal panel 4 by superposing two sets of the light source 1a, lb and the backlight light guide plates 2a, 2b. This method of switching the directivity of the illumination light by using the light deflecting effect of the above-mentioned method eliminates the need for an expensive switchable shirt element. Since the adjustment is performed only by adjustment, it is difficult to obtain sufficient directivity in the above-described method in which the directivity of the illumination light can be clearly defined by the shutter element and the collimator lens. In the example of JP-A-2001-666547, the angle of light emitted from the light guide plate is distributed around 60 to 80 degrees with a peak of 70 degrees. It is conceivable that the light guide plate will vary to some extent depending on the shape of the light guide plate and the light extraction structure.In order to obtain uniform brightness while maintaining the light emission angle constant within this range, an advanced light guide plate is required. Shape design and shape restrictions are required. For this reason, the directivity is reduced and crosstalk between left and right is likely to occur, and in order to obtain a good light distribution characteristic, the light guide plate must be connected to the light guide plate as disclosed in Japanese Patent Application Laid-Open No. 2001-66657. There were problems such as the need to prepare a set. i

As described above, in the conventional stereoscopic display device, the method of using glasses is troublesome to wear glasses, and the method of using lenticular and parallax barriers is not a method of using glasses when using glasses. The resolution or brightness of the planar image was reduced. In the conventional method of switching the light directivity, a method using a switching shirt element and a collimating lens requires an expensive switching shirt element, resulting in high cost. In addition, direct control of directivity using a light guide plate is difficult to control, direct crosstalk is likely to occur, and two knocklights are used. I was learning.

The present invention solves such a problem, and can realize a high-quality stereoscopic image with no reduction in resolution for both stereoscopic and planar images and with few problems such as crosstalk, and is simple and low-cost. Another object of the present invention is to provide a display device that can perform stereoscopic viewing and simultaneously display different screens on the same screen without using glasses suitable for a portable information terminal. Disclosure of the invention

A display device according to the present invention includes a light guide plate and light sources respectively disposed on two light incident end faces facing the light guide plate, and a light guide plate disposed on a light exit surface side of the light guide plate, and a light guide plate facing the light guide plate. A double-sided prism sheet having a triangular prism array extending in a direction parallel to the light incident end face of the light guide plate, a cylindrical lens array extending in parallel with the triangular prism array on a surface facing the surface, And a transmissive display panel arranged on the light exit surface side of the light source. The light from the light source is shifted left and right in synchronization with the left and right parallax images alternately displayed on the transmissive display panel by a synchronous driving means. Out of the transmissive display panel at an angle corresponding to the parallax of As a result, the light guide plate and the light sources respectively arranged on the two different light-entering end faces thereof, and the light guide plate arranged on the light exit surface side of the light guide plate and facing the light guide plate are provided on the light exit surface side of the light guide plate. A double-sided prism sheet having a triangular prism array extending in a direction parallel to the light incident end face, a cylindrical lens array extending parallel to the triangular prism array on a surface facing the above-mentioned surface, and a double-sided prism sheet. A transmissive display panel disposed on the exit surface side; and a synchronous driving unit for displaying a parallax image in synchronization with the light source on the transmissive display panel, wherein light from the light source is converted into a right and left parallax. Since the light is emitted from the transmissive display panel at a corresponding angle, there is an effect that a high-quality stereoscopic view with little crosstalk and different screens can be simultaneously displayed on the same screen. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a side view for explaining main parts of a display device according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram for explaining an operation of the display device according to the first embodiment of the present invention.

FIG. 3 is a characteristic diagram showing light distribution characteristics of light emitted from the light guide plate and the display panel of the display device according to the first embodiment of the present invention.

FIG. 4 is a configuration diagram for explaining a transmitted light path of a double-sided prism sheet used in the display device according to the first embodiment of the present invention.

FIG. 5 is a configuration diagram for explaining the operation of the double-sided prism sheet used in the display device according to the first embodiment of the present invention.

FIG. 6 is a configuration diagram for explaining focal positions of lenses of a cylindrical lens array formed in a double-sided prism sheet used in the display device according to the first embodiment of the present invention. FIG. 7 is a configuration diagram for explaining the angle defining action of the double-sided prism sheet used in the display device according to Embodiment 1 of the present invention.

FIG. 8 is a characteristic diagram showing light distribution characteristics of a double-sided prism sheet used in the display device according to Embodiment 1 of the present invention.

FIG. 9 is a configuration diagram for explaining conditions for calculating light distribution characteristics of the double-sided prism sheet according to Embodiment 1 of the present invention.

FIG. 10 is a characteristic diagram showing light distribution characteristics of a prism sheet shown as a comparative example for explaining Embodiment 1 of the present invention.

FIG. 11 is a configuration diagram for explaining an optical path change due to the thickness and pitch of a double-sided prism sheet as a comparative example in Embodiment 1 of the present invention.

FIG. 12 is a configuration diagram for explaining an optical path change due to the thickness and pitch of a double-sided prism sheet as a comparative example in Embodiment 1 of the present invention.

FIG. 13 is a characteristic diagram for explaining changes in light distribution characteristics when the thickness and pitch of the double-sided prism sheet change in Embodiment 1 of the present invention.

FIG. 14 is a characteristic diagram for explaining changes in light distribution characteristics when the thickness and pitch of the double-sided prism sheet are changed in Embodiment 1 of the present invention.

FIG. 15 is a characteristic diagram for explaining changes in light distribution characteristics when the thickness and pitch of the double-sided prism sheet change in Embodiment 1 of the present invention.

FIG. 16 is a configuration diagram for explaining an optical path change according to the prism angle of the triangular prism array formed on the double-sided prism sheet in the first embodiment of the present invention. FIG. 17 is a characteristic diagram for explaining a change in light distribution characteristics when the prism angle of the triangular prism array formed on the double-sided prism sheet changes in Embodiment 1 of the present invention.

FIG. 18 is a characteristic diagram for explaining a change in light distribution characteristics when the prism angle of the triangular prism array of the double-sided prism sheet changes in Embodiment 1 of the present invention.

FIG. 19 is a characteristic diagram for explaining a change in light distribution characteristics when the prism angle of the triangular prism array of the double-sided prism sheet changes in Embodiment 1 of the present invention.

FIG. 20 is a front view for describing an electronic information device according to Embodiment 2 of the present invention.

FIG. 21 is a configuration diagram for explaining a mobile phone according to Embodiment 3 of the present invention.

FIG. 22 is a configuration diagram for explaining a conventional stereoscopic display device using a light source arrangement and a collimating lens.

FIG. 23 is a side view for explaining a conventional stereoscopic display device by backlight light distribution control. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, in order to explain this invention in greater detail, the preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Embodiment 1

FIG. 1 is a side view for explaining a display device for a portable information device according to a first embodiment of the present invention.

In FIG. 1A, la and lb are light sources, 2 is a light guide plate having a rectangular side surface and an overall flat plate shape, and has a predetermined width in a direction orthogonal to the paper surface. this Light sources 1a and lb are arranged on both light incident end face sides of the light guide plate 2 so as to face each other. Reference numeral 2a denotes light extraction means formed on the surface of the light guide plate 2 by reflection printing, surface roughening, or the like.

Reference numeral 3 denotes a double-sided prism sheet disposed on the exit surface of the light guide plate 2, reference numeral 4 denotes a transmissive liquid crystal panel, and a hatched portion denotes a liquid crystal layer.

Reference numeral 5 denotes control means for controlling the synchronization of the display switching of the parallax images between the light sources 1 a and 1 b and the transmissive liquid crystal panel 4.

FIG. 1B is an enlarged side view showing the shape of the double-sided prism sheet 3. FIG. The double-sided prism sheet 3 is formed of a material having a refractive index of 1.5, and has a triangular shape formed of an isosceles triangle having a vertex angle K of 60 degrees with a ridge line extending in a direction parallel to the light incident end face of the light guide plate 2 on the lower surface. A prism array 32 is arranged so as to extend in a direction perpendicular to the plane of the paper, and a cylindrical lens array 31 extending in a direction parallel to the triangular prism array 32 (a direction orthogonal to the plane) is provided on the upper surface. It is arranged with the same pitch P as the shape prism row 32. The curvature is adjusted so that the focal position of each lens that forms the cylindrical lens array 31 coincides with the vertex of the triangular prism array 32 on the lower surface, and the pitch P of the cylindrical lens array 31 on the upper surface and both sides are adjusted. The thickness L of the prism sheet 3 is configured such that the value of (thickness L / pitch P) is 3.

Hereinafter, the stereoscopic operation will be described with reference to FIG. In FIG. 2A, only the left light source 1a is on, and the right light source 1b is off. In this case, the light emitted from the light source 1a propagates in the light guide plate 2 and is extracted out of the light guide plate 2 by the light extraction means 2a installed in the light guide plate 2. At the time when the light emitted from the light guide plate 2 is emitted, the light distribution is such that the emission angle is largely deviated toward the side opposite to the light source 1a, as shown in the light distribution characteristics shown in FIG. 3A. In FIG. 3, the horizontal axis represents the light emission angles of the light sources 1a and 1b, and 0 degrees represents the front direction (the normal direction of the transmissive liquid crystal panel). The angle inclined to the side is the + direction, and the vertical axis is the luminance (unit: cd / m ² ). When light having such an angular distribution is transmitted through the double-sided prism sheet 3, the light is refracted and reflected by the double-sided prism sheet 3 so that, as shown in FIG. It has a strong intensity in the range of degrees, and has a light distribution that hardly emits light in the range from 0 degrees to 15 degrees on the right. Thereafter, the light passes through the transmissive liquid crystal panel 4 and is emitted toward the observer as shown in FIG. 2A while maintaining the light distribution. If the distance between the left eye 6a and the right eye 6b of the observer is about 65 mm, and the viewing distance from the transmissive liquid crystal panel 4 to the observer is about 30 Omm, the center of the transmissive liquid crystal panel 4 The angle between the straight line connecting the left eye 6a or the right eye 6b and the normal direction of the transmissive liquid crystal panel 4 is about 6 degrees. That is, when the viewing distance is 300 mm, the light emitted from the transmissive liquid crystal panel 4 has sufficient intensity in the leftward direction of 6 degrees, and hardly emits light in the rightward direction of 6 degrees. With the distribution, the image is recognized by the left eye 6a of the observer, but the light does not reach the right eye 6b and the image is not recognized. With the light distribution shown in Fig. 3B, it is possible to make the image recognized only by the left eye 6a of the observer. On the other hand, as shown in Fig. 2B, if the left light source 1a is turned off and only the right light source 1b is turned on, contrary to the case of Fig. 2A, the observer's right eye 6b Only images are recognized. Therefore, if the light sources 1a and 1b are alternately turned on and the parallax images on the left and right are displayed on the transmissive liquid crystal panel 4 in synchronization with the lighting of the light sources 1a and lb by the synchronization control means 5, the observer's view can be obtained. Different parallax images can be recognized by the left eye 6a and the right eye 6b, and stereoscopic viewing by parallax becomes possible.

Furthermore, if the observer views from an angle of 8 degrees diagonally right instead of in front of the panel, the right eye will be at 16 degrees right and the left eye will be at 2 degrees right. In this case, only the right eye image is recognized as a normal plane image by the left and right eyes. Also, when the observer views from an angle of 8 degrees left, the left eye is 16 degrees left and the right is 2 degrees left. You will come to the right position. In this case, only the image for the left eye is recognized as a normal plane image by the left and right eyes. At this time, if completely different images are displayed alternately in synchronization with the lighting of the right-eye light sources 1a and 1b, two different images will be recognized at the same time on the same screen, depending on the viewing angle of the observer. can do.

Next, the operation of the double-sided prism sheet 3 will be described in detail with reference to FIGS. FIG. 4 is a view showing a transmission optical path of the double-sided prism sheet, FIG. 5 is a view for explaining the operation of the double-sided prism sheet, and FIG. 6 is a view for explaining a focal position of a cylindrical lens of the double-sided prism sheet. FIG. 7 is a diagram for explaining the angle defining action of the double-sided prism sheet. In FIG. 4, light emitted from the light guide plate 2 inclined rightward is formed on the double-sided prism sheet 3. Triangular prism row 3 2 prism slope 3

The light enters the double-sided prism sheet 3 from 2a, is reflected upward by total reflection on the inclined surface 3 2b, and passes through the cylindrical lens array 3 1 (A is the optical axis of each lens) immediately above the upper surface. It passes through the optical path 1 ◦ 1 as emitted. If the intersection of the optical path line reflected by the slope 3 2 b and the horizontal plane C including the vertex B of the prism of the triangular prism array 32 formed on the double-sided prism sheet 3 is assumed to be 102. The light passing through the optical path 101 is equivalent to the light emitted from the intersection 102 and directly entering the cylindrical lens array 31. From this, all the light totally reflected by the slope 3 2 b and incident on the cylindrical lens array 31 directly above is emitted from the region 103 in FIG. 5, and the cylindrical lens array 31 directly above It can be replaced by light incident on. The prism row is indicated by a broken line in the figure.

The shape of 32 prism is shown.

In addition, the light that is totally reflected by the slope 32 b and enters the cylindrical lens array 31 directly above, is emitted from the region 104 in FIG. 5, and is directly above the cylindrical lens array 31. It can be seen that there is no light passing through the same optical path as the light incident on the row 3 1. If the focal position of the cylindrical lens array 31 is matched with the vertex B of the prism of the triangular prism array 32 as shown in Fig. 6, the cylindrical lens is totally reflected by the slope 32b and is directly above The light incident on the row 3 1 is emitted from the right side of the optical axis A of the cylindrical lens row 3 1 on the horizontal plane C including the focal point of the cylindrical lens row 3 1 and is incident on the cylindrical lens row 3 1 directly above. As shown in Fig. 7, light emitted from one point on the horizontal plane C including the focal point of the lens of the cylindrical lens array 31 and directly incident on the cylindrical lens array 31 directly above is The light emitted from the cylindrical lens 31 at an angle 6> represented by the following equation (1) according to the distance d from the optical axis A of the cylindrical lens 31 to the light emitting point, and the position and the light emission of the light emitting point The angles correspond one-to-one.

6> =-A r c T a n (n d / L) (1)

Here, n is the refractive index of the material forming the double-sided prism sheet 3, L is the thickness of the double-sided prism sheet 3, and is the focal length of the lens of the lens array 31.

Therefore, all light emitted from the right side of the optical axis A on the plane C is emitted while being inclined leftward. In other words, the light totally reflected by the slope 3 2b and incident on the cylindrical lens 3 1 immediately above is emitted only to the left after passing through the cylindrical lens 31 and, as shown in FIG. 3B, Light distribution with sharp left and right separation characteristics can be obtained at the boundary of the normal direction. This has been proposed by the University of Kentucky as described above, and as disclosed in Japanese Patent Application Laid-Open No. Hei 5-107636, a directivity control method using a divided light source and a lens has been proposed. Directivity control is similar, and accurate directivity control can be realized without using expensive liquid crystal shirt elements, thus enabling three-dimensional display with less crosstalk. Here, FIG. 8 is a characteristic diagram showing a result obtained by performing a simulation on the light distribution characteristics of the double-sided prism sheet 3. The horizontal axis represents the angle of incidence on the double-sided prism sheet 3, and the vertical axis represents the amount of light emitted from the viewing region of both eyes (arbitrary scale, numerical values used in the simulation). The solid line indicates the amount of light emitted to the left-eye viewing area, and the broken line indicates the amount of light emitted to the right-eye viewing area.

The simulation was performed by injecting light with a fixed angle into a single double-sided lens sheet 3 as shown in FIG. 9 and calculating the angular distribution of the emitted light.

In FIG. 9, θ 1 is the angle of incidence on the double-sided prism sheet 3, and areas A and B are the visible areas of the left and right eyes within the ranges of 0a = 4.5 degrees and 0b = 10 degrees, respectively. .

Fig. 8 shows a triangular prism 31 made of a material having a refractive index of about 1.5, as shown in Fig. 9B. A simulation is performed on a double-sided lens sheet 3 that has a ratio of 1: 3 to the lens L and is configured so that the focal point of the lens of the cylindrical lens array 3 1 is located at the vertex of the triangular prism. The horizontal axis indicates the light incident angle, and the vertical axis indicates the amount of light emitted to the visible range from 4.5 to 10 degrees to the left and from 4.5 to 10 degrees to the right, corresponding to the left and right eyes. Is plotted on an arbitrary scale. The solid line in FIG. 8 indicates the amount of light emitted to the left-eye viewing area, and the dashed line indicates the amount of light emitted to the right-eye viewing area. The angle of light incident on the left and right eyes is determined by the viewing distance, and is about 9 degrees at 200 mm, about 6 degrees at 300 mm, and about 4.5 degrees at 400 mm. Here, assuming a portable information device, the characteristics are evaluated using light with an emission angle of 4.5 degrees to 10 degrees corresponding to a viewing distance of 200 mm to 400 mm. From Fig. 8, the horizontal direction is 50 degrees to 80 degrees. It can be seen that light at an incident angle of? Is emitted to the viewing range, and light at other incident angles is hardly emitted to the viewing range.

When performing stereoscopic vision, if the light that is supposed to be guided to the left eye reaches the right eye, crosstalk will occur between the left and right eyes, impairing the stereoscopic effect. Therefore, if the areas of the incident angles of the light guided to the left and right eyes overlap, it is not possible to see them stereoscopically, and even if they do not overlap, if they are close to each other, they will not It is necessary to input light with sharp light distribution characteristics that can sufficiently separate light. In the case of the characteristics shown in Fig. 8, there is an area that does not emit light within the visible range for both the left and right eyes over a wide incident angle range of ± 40 degrees across the normal direction. Therefore, the light incident on the double-sided prism sheet 3 does not require a particularly sharp light distribution. Therefore, a special configuration of the light guide plate 2 and a complicated design for controlling the light distribution before entering the double-sided prism sheet 3 are not required.

Here, the light distribution characteristics of a lens sheet having no cylindrical lens array disclosed in Japanese Patent Application Laid-Open No. 2001-66547 are shown in FIG. 10 as a comparative example. The solid line in FIG. 10 indicates the amount of light emitted to the left-eye viewing area, and the broken line indicates the amount of light emitted to the right-eye viewing area. The horizontal axis in FIG. 10 is the light incident angle on the prism sheet, and the vertical axis is the amount of emitted light (arbitrary scale, 'the numerical values used in the simulation). In the structure of the lens sheet of this comparative example, as disclosed in Japanese Patent Publication No. 2001-6657, the prism has a refractive index of 1.57 and the vertex angle of the prism is øa = b = 34. 5 degrees.

In Fig. 10, the incident angle range of the light guided to the left and right eyes is narrow, about 10 degrees in width, and when light inclined from the optimal area enters, the angle difference is about 5 degrees, It can be seen that light guided to the eye of the user is emitted. For this reason, it is necessary to make the light emitted from the light guide plate have a sharp light distribution characteristic that matches this optimum incident angle range. ヅ It was necessary to use a cryed structure.

Also, the light distribution may vary depending on the thickness L and the pitch P of the double-sided prism sheet 3, and crosstalk may easily occur. For example, when the ratio of pitch to thickness (thickness L / pitch P) is small, as shown in Fig. 11, the light 107 that directly enters the cylindrical lens array 31 from the slope 32a is May enter the viewing area. The broken line in FIG. 11 shows a configuration in which the ratio of the pitch to the thickness (thickness L / pitch P) is 3 as described above.

Also, even if the ratio between the pitch and the thickness becomes too large, as shown in FIG. 12, the light is totally reflected by the slope 3 2 d next to the triangular prism array 32 and the cylindrical lens array 3 1 There is a possibility that the light 109 incident on the image may enter the viewing area. In both cases, the intersection of the optical path line of the incident light entering the lenses in the cylindrical lens array and the horizontal plane C including the vertices of the prisms in the triangular prism array is opposite to the light passing through the regular optical path with respect to the optical axis A. Side, so crosstalk may occur. The dashed line in FIG. 12 shows the configuration in the case where the ratio between the pitch and the thickness (thickness L Z pitch P) is 3, similarly to the dashed line in FIG.

Figs. 13 to 15 show the light distribution characteristics of the double-sided prism sheet 3 when the ratio of the pitch P to the thickness L (thickness LZ pitch P) of the double-sided prism sheet 3 was changed by 1.7. The results of plotting are shown in the same manner as in FIG. FIGS. 13A and 13B show the above ratios of 1.7 and 2.3, and FIGS. 14A and 14B show the above ratios of 2.7 and 4.0. 5A and 15B respectively show the light distribution characteristics of the double-sided prism sheet 3 when the above ratio is 4.3 and 4.7. In these figures, the horizontal axis represents the angle of incidence on the double-sided prism sheet 3, and the vertical axis represents the amount of emitted light (arbitrary scale and numerical values used in simulation). The solid line indicates the amount of light emitted to the left-eye viewing area, and the broken line indicates the amount of light emitted to the right-eye viewing area.

From Fig. 13, when the thickness Z pitch is in the range of 2.7 to 4.0, Although the distribution of the surroundings slightly changes, there is no significant change in the angular characteristics having a region where light is not emitted to either the left or right eye over the range of the incident angle ± 40 degrees. If the thickness / pitch is 2. 7 yo Ri small no longer 2.3, a small peak _(appears click to the incident angle range of about 3 0 degrees 0 degrees, the 1. In 7 rather large peak. This It is considered that this is due to the influence of light due to the light path such as light 107 shown in Fig. 11. If there is a peak that emits light in the viewing area in this incident angle range, the left and right sides are effective for left and right separation. It is not preferable because the area where light is not emitted is narrowed within the viewing range for both eyes, and when the thickness Z pitch is 4.3, the incident angle is in the range of about 50 to 60 degrees. However, a peak causing crosstalk occurs, and the height of the peak increases as the thickness becomes larger, because of the influence of light due to the light path such as light 109 shown in FIG. Therefore, when the thickness pitch is in the range of 2.3 or less and in the range of 4.3 or more, It is expected that loss talk will increase, and it is understood that it is preferable to use the thickness Z pitch in the range of about 2.5 to 4.0. Thus, the thickness / pitch is about 2.5 to 4.0. By using it within the range, higher-quality three-dimensional display can be performed.

Further, when the apex angle of the prisms of the triangular prism row 32 formed on the double-sided prism sheet 3 changes from the angle shown by the solid line to the angle shown by the broken line, as shown in FIG. Even if the light passes through the same optical path after being reflected, it will have different optical paths like optical paths 112 and 113 before being totally reflected, and the incident angle to the double-sided lens sheet 3 will be It will be different.

For this reason, it is conceivable that the optimum incident angle range for emitting light to the viewing area may change. If the area that does not emit light within the viewable range for either the left or right eye becomes narrow due to the change in the incident angle range, crosstalk is likely to occur, and 60 degrees as shown in Fig. 3A. Especially in the range from If the matching with the light distribution in the backlight light guide plate from which many lights are emitted is deteriorated, the efficiency is lowered, which is not preferable.

Figs. 17 to 19 show the light distribution characteristics of the double-sided prism sheet 3 when the apex angle φa = φb of the prisms of the triangular prism row 31 is changed in the same manner as in Fig. 8. The plotted results are shown. Fig. 17A and Fig. 17B show prism apex angles a = øb of 35 and 34 degrees, Figs. 18A and 18B show prism apex angles øa = øb Fig. 19A and Fig. 19B show the light distribution characteristics of the double-sided prism sheet 3 when the prism apex angle 0a = b is 28 degrees and 27 degrees. It is showing it. The horizontal axis in FIGS. 17 to 19 is the angle of incidence on the double-sided prism sheet 3, and the vertical axis is the amount of emitted light (arbitrary scale, numerical values used in the simulation). The solid line indicates the amount of light emitted to the left-eye viewing area, and the broken line indicates the amount of light emitted to the right-eye viewing area.

From Fig. 1 to Fig. 19, it is clear that the range of incident angle of visible light almost covers the range of 60 degrees to 80 degrees where a large amount of light is emitted from the backlight. 0a = b ranges from 28 degrees according to FIG. 19A to 34 degrees according to FIG. 17B. Further, when 0a = 0b is more than 31 degrees according to FIG. 18A, the light is emitted to the viewable range in a region where the light is not emitted within the viewable range for both the right and left eyes within ± 40 degrees. 0a = 0b is at least in the range of 28 to 34 degrees, more preferably in the range of 28 to 30 degrees, since the proportion of light that is emitted tends to increase gradually. Desirably.

When the apex angle of the lower surface prism of the double-sided prism sheet is configured in this manner, crosstalk is further reduced, the light utilization efficiency of the light emitted from the backlight is increased, and a bright and high-quality three-dimensional display can be performed.

In this way, the light sources la and lb are turned on alternately, and a double-sided prism sheet By controlling the directivity of the light using 3 and displaying the left and right parallax images on the transmissive liquid crystal panel 4 in synchronization with this, high-quality stereoscopic viewing can be performed with a simple configuration. Also, when displaying a planar image, if both the light sources 1 a and lb are turned on and the image is displayed on the transmissive liquid crystal panel 4, a high-quality planar image can be displayed without lowering the resolution and the like.

In the first embodiment, the focal position of the lens of the cylindrical lens array 31 formed on the double-sided prism sheet 3 is set to a position that coincides with the vertex of the prism of the triangular prism array 32, and the angle of the emitted light Although the control method is adopted, the focal length of the lens of the cylindrical lens array 31 is set to be shorter, and on the horizontal plane C including the apex of the prism of the triangular prism array 32 at the position of the observer's eye. A configuration in which a virtual light source is transferred can also be adopted. When the display area is sufficiently larger than the distance between the left and right eyes of the observer, the pitch of the cylindrical lens row 31 and the triangular prism row 32 is changed according to the position in the double-sided prism sheet 3, Good left-right separation characteristics can be obtained over a wide surface.

According to the first embodiment described above, a high-quality parallax image with little crosstalk and the like can be presented to the left and right eyes separately, and high-quality display can be performed without a decrease in resolution in both the stereoscopic display and the planar display. There is an effect that a device can be obtained.

In the first embodiment, since it is difficult to change the pitch of the double-sided prism sheet 3 and the positional relationship between the cylindrical lens row 31 and the triangular prism row 32 after construction, it is difficult for the observer to change the position. It is difficult to actively control the light distribution characteristics according to the position and to expand the stereoscopic viewing area. Therefore, the observer controls the observation position by moving the device by hand, which is particularly suitable for portable information devices. Embodiment 2

FIG. 20 is a front view for explaining an electronic information device according to Embodiment 2 for carrying out the present invention. Here, the inside of the electronic information device is displayed around the display device to explain the details of the display device.

In FIG. 20, light sources la and lb are arranged on the left and right sides of the light guide plate 2 in the main body 10 of a portable electronic organizer, which is an electronic information device, so as to face each other. The light source 1 is composed of a light emitting diode 8 and a light guide 9, and the light emitted from the light emitting diode 8 travels through the light guide 9 and emits light little by little toward the light guide plate 2 to uniformly guide the light. Light is emitted to the side of the light plate 2.

Reference numeral 3 denotes a double-sided prism sheet disposed on the light exit surface of the light guide plate 2, and the triangular prism array and the cylindrical prism array extend in the vertical direction. 4 is a transmissive liquid crystal panel placed on a double-sided prism sheet. 1 1 is an operation button.

Hereinafter, the operation will be described with reference to FIG. When the light sources 1a and 1b are alternately turned on and the parallax images on the left and right are displayed on the transmissive liquid crystal panel 4 in synchronization with the light sources la and lb by the synchronization control means 5 (not shown), When is located in front of the transmissive liquid crystal panel 4, the observer's left eye 6a and right eye 6b can recognize different parallax images, and stereoscopic viewing with parallax becomes possible.

In addition, when the observer tilts the portable information terminal 10 and looks at it from an angle of 8 degrees diagonally right instead of in front of the transmissive liquid crystal panel, the right eye is at 16 degrees right and the left eye is at 2 degrees right. Will be. In this case, only the image for the right eye is recognized as a normal plane image by the left and right eyes. Also, if the observer views from an angle of 8 degrees to the left, the left eye will be at 16 degrees left and the right will be at 2 degrees left. In this case, only the image for the left eye is recognized as a normal plane image by the left and right eyes. At this time, if completely different images are alternately displayed in synchronization with the lighting of the right-eye light sources 1a and 1b, two different images can be recognized depending on the viewing angle of the observer.

These display functions are completely different from the image data, but are related to the content, such as maps and directions, e-mail documents and attached file photos, and two product photos. When comparing specifications, it is effective because it is possible to compare with natural movement without manipulating a finger. Embodiment 3.

FIG. 21 is a configuration diagram for explaining an electronic information device and a display device according to a third embodiment for carrying out the present invention.

In FIG. 21, the display device according to the first embodiment is arranged in a mobile phone 12 which is an electronic information device. Here, the display device is arranged so as to display different images vertically. That is, the light sources 1 c and 1 d are arranged above and below the light guide plate 2 so as to face each other. Reference numeral 3 denotes a double-sided prism sheet disposed on the light exit surface of the light guide plate 2, and the triangular prism array and the cylindrical prism array extend in the left-right direction. 4 is a transmissive liquid crystal panel placed on a double-sided prism sheet. Other details of the display device are the same as those of the first embodiment, and a description thereof will not be repeated. 1 1 is an operation button.

Hereinafter, the operation will be described with reference to FIG. If the light sources 1 c and 1 d are turned on alternately, and two different images are displayed on the transmissive liquid crystal panel 4 by the synchronization control means 5 (not shown) in synchronization with the lighting of the light sources lc and Id, When the observer tilts the mobile phone 12 and looks not from the front of the transmissive liquid crystal panel but from an angle of 2 degrees to 14 degrees, for example, an upper 6 degrees, the left and right eyes are both In this case, only the image when the light source 1c arranged on the upper side is lit is recognized as a normal planar image. Also, if the observer views from an angle between 2 degrees and 14 degrees below, for example, 6 degrees below, both the left and right eyes will come to the position of 6 degrees below. In this case, only the image when the light source 1d arranged below the left and right eyes is turned on is recognized as a normal planar image. At this time, if completely different images are alternately displayed in synchronization with the lighting of the light sources 1c and 1d, two different images can be recognized depending on the viewing angle of the observer.

In the case of such a configuration in which the light sources are arranged vertically, the left and right images do not differ from each other, and the left and right eyes do not recognize different images at the same time, so the two images are mixed in a wide angle range. There is no single clear image visible. Also, since the viewing angle is wide, the observer does not need to fix his wrist at a narrow angle, so holding the mobile phone is easy.

In addition, when the mobile phone shown in Fig. 21 is turned sideways, the parallax image is projected as two images, and when the observer views from the front of the transmissive liquid crystal panel of the mobile phone 12, the stereoscopic image can be visually recognized. Needless to say. In this case, the parallax image should be displayed so that the right-eye image of the parallax image enters the right eye and the left-eye image enters the left eye, and the parallax image to be displayed faces up and down correctly. It is.

Further, although the present embodiment has been described using a mobile phone, it goes without saying that the present invention can be used for other mobile information terminals. Industrial applicability

According to the present invention, it is possible to obtain a display device suitable for a portable information terminal and capable of performing stereoscopic viewing and simultaneously displaying different screens on the same screen.

Claims

The scope of the claims

1. A light guide plate and light sources respectively arranged on two different light incident end surfaces thereof, and a light guide surface arranged on the light exit surface side of the light guide plate, and a direction parallel to the light incident end surface of the light guide plate on a surface facing the light guide plate. A double-sided prism sheet having a triangular prism array extending in parallel with the above-mentioned surface, and a cylindrical lens array extending in parallel with the triangular prism array, and a transmission disposed on the exit surface side of the double-sided prism sheet. Type display panel, and synchronous driving means for displaying two different images on the transmissive display panel in synchronization with the light source, wherein light from the light source is transmitted from the transmissive display panel in different directions to the left and right, respectively. A display device which emits light.

2. The display device according to claim 1, wherein the light from the light source is emitted from the transmissive display panel at an angle corresponding to the right and left parallax.

3. A light guide plate and light sources respectively arranged on two different light incident end faces thereof, and a light source arranged on a light exit surface side of the light guide plate, and a surface facing the light guide plate being parallel to a light incident end face of the light guide plate. A double-sided prism sheet having a rectangular prism array extending in the direction, a cylindrical lens array extending in parallel with the triangular prism array on a surface facing the above-described surface, and a double-sided prism sheet is disposed on the exit surface side. A transmission type display panel, and synchronous driving means for displaying two different images on the transmission type display panel in synchronization with the light source. A display device which emits light from a panel.

4. The display device according to claim 1, wherein the focal position of the cylindrical lenses forming the cylindrical lens array is set to coincide with the vertices of the prisms forming the triangular prism array.

5. The display device according to claim 1, wherein the ratio of the pitch of the cylindrical lens array to the thickness of the double-sided prism sheet is in the range of 1: 2.5 to 1: 4.

6. The display device according to claim 1, wherein the apex angles of the prisms in the triangular prism row are in a range of 56 degrees to 68 degrees.

7. An electronic device comprising the display device according to claim 1. +